Tools of the kind discussed herein relate, in particular, to tools equipped with a coolant/lubricant supply system intended for on one hand, cooling/lubricating the workpiece surface being worked on and, on the other hand, for activating an actuation unit of the tool that is provided with an actuation element and an actuation medium. Actuation units of the kind referred to here serve to activate the supplementary functions of the tool, for example the insertion and removal of supplementary elements that serve as a partial tool and are capable of performing special machining operations. Tools with such actuation units can be used, for example, to produce a recess in the wall of a borehole or to work on a valve seat in the engine block of an internal combustion engine and in direct relation therewith to work a valve stem guide. It has been found that a recirculating coolant/lubricant contains contaminants, for example silicon particles, formed during the machining of workpieces and that are deleterious to the actuation unit because they cause considerable wear and the freezing of movable parts of such a unit. For this reason, expensive filtration measures are needed to limit this drawback. Without a major expense, however, wear manifestations cannot be entirely prevented.
Also known is a tool for the machining of workpieces (DE 100 44 972 A1) that is provided with a coolant/lubricant supply system and has an actuation unit with an actuation element and an actuation medium circuit. The actuation unit is separated from the coolant/lubricant supply. The separation is brought about by the fact that the coolant/lubricant supply is associated with the cutters of the tool and serves to provide the cutters used for the machining of the workpiece with coolant/lubricant. The actuation device has its own supply of medium, separated from the coolant/lubricant supply, and is supplied with compressed air or hydraulic liquid. The tool thus distinguishes itself, on the one hand, by a coolant/lubricant supply and, on the other, by a separate supply of compressed air or hydraulic liquid, which makes the tool assembly expensive.
Hence, the object of the invention is to provide a tool of the afore-mentioned kind that avoids these drawbacks.